Monday, June 16, 2014

Pan Magazines

In our last post, we studied the drum magazine. In today's post, we will study another type that looks very much like the drum magazine, but operates a bit differently. Today's object of study will be the pan magazine.

The pan magazine is a flat cylindrical shape, similar in shape to a drum magazine. However, if you look at the previous post, drum magazines are mounted from below the gun. A pan magazine, on the other hand, is mounted on top of the gun and uses the force of gravity to drop cartridges into the action. One more difference is that the cartridges in a pan magazine are arranged perpendicular to the axis of rotation, whereas the cartridges in a drum magazine are arranged parallel to the axis of rotation. The easiest way to understand it is via some pictures.

One of the first firearms to feature a pan magazine, was the Bira gun, which we studied many months ago.

A Bira Gun. Click on the image to enlarge.

The flat circular object that you see on top of the gun is the pan magazine. In the Bira gun, this magazine is designed to hold .577-450 Martini cartridges in two layers of 60 cartridges each, giving the magazine a capacity of 120 cartridges. As the crank (which can be seen on the side at the rear of the gun) is turned, the magazine is rotated via a ratchet mechanism. There is a stationary plate at the bottom of the pan, which has a slot in it, big enough for a cartridge to fall through into the action.

Another gun that features a pan magazine was invented in 1898 by Howard Carr, a well-known shooter (he once held a world-record for pistol shooting), and manufactured by the San Francisco Arms Company. The details of his patent may be viewed here.

In the above drawing, note how the cartridges sit on top of each other in the magazine. This allows the magazine to hold a large number of cartridges.

Some other guns that feature pan magazines are the Lewis gun, the Bren light machine gun, the Degtyarev light machine gun and the American-180 submachine gun.

A Lewis gun. Click on the image to enlarge. Public domain image.

A Degtyarev gun. Click on the image to enlarge. Image copyright Polish Ministry of National Defense and used with permission.

In the case of the Bira gun and the Lewis gun, the pan magazine has notches or teeth on the outside of the magazine cover, which can be driven by a ratchet and pawl mechanism. In the case of a Bren gun or an American-180, the magazine is rotated by unwinding a circular spring.

Like drum magazines, pan magazines can hold a pretty large number of cartridges. The Bira gun's capacity is 120 cartridges, the Howard Carr machine gun magazine holds 310 cartridges, the Bren magazine holds 100 cartridges, the Lewis gun holds 47 or 97 cartridges, the Degtyarev holds 47 or 60 cartridges and the American-180 can hold 165, 177, 220 or 275 cartridges, depending on the model of magazine. Since a pan magazine sits flat on top of the gun, this means the gun doesn't take up too much vertical height and this allows the soldier to lie prone on the ground without exposing himself much.